A. There's no official interface to view Windows Phone 7 applications, but you can easily view Windows Phone 7 applications using Bing's visual search capability.
Go to bing.com and perform a search for "Windows Phone 7 Apps." Once the results are shown, select the "Visual Search" tab. You can now see applications, browse by top applications, and select categories, as shown below.
It's a nice interface, but you can't buy the applications—you still need to use your Phone or Zune for that.